The combat system of Infinite Horizons is based on the skill system. However, there are large groups of weapon skills which are very similar, and it is much easier to describe these groups of skills once, rather than repeat pages of description with tiny changes for each different weapon, so we will do that in this chapter.
Combat is divided into two time units: a jiffy and a round. A jiffy is one half of a second. A round is ten jiffies, or five seconds long. Most combat timings are done in jiffies, but rounds are used for actions with a longer duration.
There are two basic types of combat: melee combat and missile combat. The special cases for each will be described independently of the general combat rules.
Melee combat is any combat in which the participants are fighting at close range. Examples of melee combat are any kind of unarmed combat (boxing, wrestling, martial arts), knife or sword fighting, and fencing.
Missile combat is any combat in which the weapons used are missiles of some sort. Some of the more common missiles which may be used are rocks, arrows, bullets, or laser beams (well, they're common in some campaigns), but there are as many different types of missiles as there are objects which can be thrown or fired.
At the beginning of an encounter, each player will roll a d10. This result may be modified by the GM according to any abnormal circumstances (i.e. characters that are being ambushed will often have their roll increased). The final result is the character's action start time.
Every action a character might chose will have a time (in jiffies) required to complete it. For attacks, this time is simply the weapon speed. For other actions, the time may be determined by the GM (just figure out how long the action would take in seconds, and double it). This time is added to the character's action start time, to give the action completion time, the time at which the chosen action will finish (for example, a blow will land or a missile will be launched).
Actions are resolved in order of their completion times. As soon as a character has finished one action, their new action start time is their old action completion time. Thus, characters using very fast weapons will often complete several attacks before opponents with slow weapons can finish one.
Sil is sparring with Rutger. Sil uses her Martial Arts skill, which gives her a weapon speed of 1 with her hands and 2 with her feet. Rutger is using his short sword, with a weapon speed of 5. At the beginning of the combat, Sil rolls a 4 and Rutger rolls a 2. Since both were at the ready, there are no modifications to these rolls. Rutger's sword attack will finish at 7(=2+5), while Sil can kick Rutger at 6(=4+2). Sil can then punch Rutger at 7(=6+1), coincident with his attack on her.
There may be some cases, such as when one character is fighting another, where it may be necessary for the players to write down their actions. This is to prevent one character from deciding what to do based on another character's actions.
If a character wants to react to another action in this way, they will have to wait until the action becomes clear (sometimes as soon as the action starts, but often not until it has completed), and may react to it (begin their own action) in the next jiffy.
Determination of the results of various actions is done according to the skill system (see the Skills chapter). For every attack (or parry, disarm, pirouette, souffle, or whatever) a character is making, the player will roll a d% against the applicable skill. This is a standard skill check (as described in the section on Skill Checks in the Introduction). Modifiers to this roll might depend on the terrain, the size of the character's opponent, wounds the character is suffering from, or other factors. A successful skill check indicates that the attack was successful, in which case damage may be done (see the section on Damage, Dismemberment and Death).
Note that an opponent which is unconscious or otherwise unable to move can be automatically hit without a die roll on any attack with a melee weapon. Naturally, most attacks against helpless opponents will be aimed attacks (as described under the Aimed Attacks heading in this section), since they are guaranteed to hit. This has the effect that most helpless characters can be killed with a single blow.
A character wanting to parry an attack can attempt to do so by going to a defensive stance and waiting for the attack to begin. The action time for a parry is 1/3 of the WS of the weapon being used to parry. A parry may not begin until the jiffy after the attack which is being parried begins (as described under the Action-Reaction heading in this section) and must end not later than the jiffy in which the attack lands. To parry a missile weapon, the attack is considered to begin when the missile is launched.
To determine if a parry is successful, the character must make a check against their skill with the parrying weapon. If the check is successful, the attack is blocked, regardless of the success or failure of the attack roll.
If a character begins an attack immediately after a parry attempt (whether the parry was successful or not), with the weapon used to parry, the attack can be completed in 2/3 the normal WS (actually, the normal WS less the parry time). Note that if damage was done, the required wait (see the section on Damage, Dismemberment and Death) will interrupt the flow, and the next attack cannot start immediately.
Continuing the example with Sil and Rutger, we recall that Rutger has a WS of 5 with his short sword. Sil quickly tired of hitting Rutger's armour with her bare hands, and has drawn her short sword. At the beginning of this combat, Sil rolls a 5 and Rutger rolls an 8. Sil begins her attack at 5, so it will land at 10. Rutger decides to parry this attack, and his parry begins at 8. The time for the parry is 1(=5/3 rounded down), so he finishes at 9. His skill check is successful, and Sil's attack is blocked. Rutger can now immediately begin an attack (at 9). His WS for this attack is 4(=5 reduced by the parry time), so it will complete at 13(=9+4). Sil's attack, despite being parried, is not completed until 10, so she wisely decides to parry Rutger's next attack, beginning at 11 and ending at 12. Since they are both quite talented, they continue for quite a while, each parrying the other's blow and then launching an attack of their own, which is parried, and so on.
There will be times when your character will want to aim for a specific hit location (see the introduction to the Race Descriptions chapter), rather than just take whatever looks open at the time. These are called aimed attacks, and they have both advantages and disadvantages.
The main advantage is that they can be used to target areas that are strategically important. For example, hit locations that are already wounded or otherwise known to be weak might be targeted in order to more quickly dispatch the foe. Aimed attacks are also used for any attempts at disarming (described in the Melee Combat section).
The main disadvantage of aimed attacks is that they are more difficult, and so are not as likely to succeed. Each aimed attack has a difficulty associated with it, which will be subtracted from the character's weapon skill before the attack is made. All races have penalties listed for each hit location, in their respective race descriptions. Other difficulties will be determined by the GM based on the situation at hand. This difficulty is over and above any others that may be assigned for moving targets or other reasons.
It could be argued that all attacks are aimed attacks, since characters are almost always aiming for somebody, but this is taken to be part of the learning of the skill at a particular skill level (this difficulty is assumed to be included already, and the difficulties assigned for other aimed attacks represent the difference from the general difficulty to the specific).